Concentration of beryllium ores



T. L. JOHNSTON CONCENTRATION 0F BERYLLIUM oREs Filed Nov. 8, 1963 Jan. 24, 1967 INVNTOR.

THEODORE L. JOHNSTON ATTORNEYS United States Patent Oice 3,300,147 Patented Jan. 24, 1'9'67 3,300,147 CONCENTRATION F BERYLLIUM ORES Theodore L. Johnston, Manitou Springs, Colo., assignor to Mineral Concentrates and Chemical Company, Inc., Denver, Colo., a corporation of Colorado Filed Nov. 8, 1963, Ser. No. 322,333 14 Claims. (Cl. 241-20) This invention relates to a process for the concentration of beryllium ores, more particularly, it relates to a flotation process for the production of high grade concentrates representing a high percentage recovery of beryllium from the ores.

The invention is illustrated by its application to the production of concentrate from beryl and from ores containing both beryl and bertrandite; however, its application is not limited to these materials as it is equally applicable to bertrandite, phenacite and other beryllium ores alone or existing together in beryllium ores.

Phenacite has the formula 2BeO-SiO2, bertrandite has the formula 4BeO-2SiO-H2O and beryl has the formula 3BeO-Al2O36SiO2- These ores :are silicates and beryllium is recovered from them in the form of beryllium oxide in concentrates. The beryllium oxide content of bertrandite is approximately 42%, of phenacite 46% while beryl contains a maximum of only 14% beryllium oxide. Beryl is by far the most common of the three minerals and exists in widely scattered areas throughout the country in pegmatite dikes and veins, and also in micaceous greisens and quartz. Beryl occurs in ores with gangue materials or minerals which are principally quartz, feldspar and mica but other minerals may occur with the ores in smaller amounts including fiuorite, tourmaline, garnet, topaz, hornblende and sometimes iron compounds. The percentage of BeO in minerals containing beryl is relatively small so that a highly effective recovery process is required to make processing of low grade ores economically feasible for beryllium recovery.

The chief difficulty attendant to the separation of beryl from the principal gangue materials, quartz, feldspar and mica, existing with it in its ore, is the similarity of physical properties of beryl with those of these gangue materials. Because of this similarity in physical properties, gravitation, electrostatic and other conventional separation methods are not particularly effective. Accordingly, any practicable method for separation of beryl from gangue materials must be highly selective for the recovery of beryl in the presence of the three principal gangfue materials. In View of the low percentage of beryllium oxide in beryl minerals a process is dictated which provides a high percentage recovery of beryllium as well as a high grade concentrate in the initial separation without the requirement of several partial separations including middlings and tailings, or repeated processing steps.

Accordingly, it is an object of this invention to provide a method for producing high grade concentrates from beryllium ore which represents a high percentage recovery of beryllium from the tore.

It is another object of this invention to provide a process for producing high grade concentrates from beryllium ore with high percentage recoveries of beryllium in a single pass without the necessity of repetitive processing.

It is `a further object of this invention to provide a continuous flotation process for the recovery of beryllium from its ores `which is economically feasible when :applied to low grade beryllium ores, such as, beryl.

In accordance with this invention, the above and other objects are accomplished by a continuous flotation process consisting of steps performed in a required sequence in which the beryllium containing ore is comminuted to a particle size between about -50 and -100 mesh, formed into a water base pulp having a solids content between about 15 and 50 percent, the pulp subjected to a conditioning treatment With an alkaline conditioning agent at a temperature between `about 5590 C. at a pH above about 9.5, a fatty :acid collecting and otation agent added to the conditioned pulp after the conditioning step, and the pulp subjected to a froth otation treatment followed by removal of the beryllium component of the ore in the froth. The preferred conditioning agent is sodium sulde and the preferred fatty acid collecting and otation agent is oleic acid, used, respectively, in -amounts corresponding to ratios of about 4 to 6 pounds per ton of ore and not more than about 25 grams per ton of ore. Preferred limitations within the above ranges are a particle size in which at least percent of the particles are -100 mesh, a 25 percent solids content for the pulp, a conditioning time for the pulp of about 2-5 minutes, and a temperature and pH for the conditioning and flotation steps of 75-80" C. and 10, respectively.

The use, in a otation process for the recovery of beryl from its ores, of sodium sulde as a conditioning agent and -oleic acid as a frothing and `collecting agent is well known and is disclosed in an article entitled, Floatability of Beryl, in the Proceedings of the Second United Nations Conference on the Peaceful Uses of Atomic Energy, volume 3, 1958, pages 162-166, written by M. A. Eigeles and I. T. Leviush. The method disclosed in this article has not gained acceptance as indicated by a report given |by Moir, Collins, Curwen and Manser at the International Mineral Processing Congress at Cannes, France, May 26- June 2, 1963 which is abstracted at page 46 of the publication, Mining Engineering for August 1963 in an abstract entitled Flotation Process. lt is stated in this abstract that the Eigeles method, the Lamb method, the Runke method and Rapid City Method were investigated as means of floating beryl. The rst three methods gave concentrates of 2% to 6% BeO, While the fourth method yielded concentrates of 13% BeO.

Attempts to obtain high grade concentrates from large scale `amounts of beryl ores using the method disclosed in the Eigeles et al. article have met with failure by the present inventor. The minimum `amount of oleic acid to be used for a ton of ore is disclosed in Table V of the above article as grams. It has been found in accordance with the present invention that if oleic acid is used on large scale amounts of ore at a ratio of more than about 25 grams per ton tof ore, irrespective of pH and temperature conditions, gangue material is floated in increasing amounts las added amounts of oleic acid are increased. Accordingly, oleic acid added in amounts in excess of about 25 lgrams per ton Iof ore ratio results in a low grade concentrate. Tests on laboratory samples of 750 grams of ore using Iamounts of oleic acid proportionate to the amounts disclosed in the article for one ton lots of ore give results closer to those disclosed in the article, indicating that the amount of oleic acid used with laboratory techniques and under laboratory conditions on small `samples may not be quite as crictical as it is for production lots `of ore. This illustrates what is frequently found -to be the case, that laboratory parameters, such as reagent amounts, somewhat satisfactory in a laboratory process cannot lbe extrapolate-d linearly to obtain acceptable parameters for a production process.

FIG. 1, a schematic flow diagram illustrating the process of the invention, will 'be referred to hereinafter in describing the invention.

The grinding, classification and sampling procedures as illustrated in the flow diagram, are, of course, conventional. Unless otherwise stated all percentages given are based lon weight.

In the practice of the invention, the ore is preferably ground to pro-duce a coinminuted product in which at least 90 percent of the particles will pass through a 100 mesh screen, that is, 90 percent of the particles are -100 mesh. However, the invention is operative if the particle size varies between -55 and 100 mesh, it bein-g an advantage of this process that de-slirning is not necessary and relatively smaller particles can be used than is possibe with prior art processes. Water is added as shown in the flow diagram prior to entry of the ore into the ball mill and the ore is wet ground. The ore particles must be carefully washed at some step prior to entry into the conditioning tank in order to remove oil, wood chips, grease and other objectionable foreign material. The water used to pulp the ground ore is softened before use. Sufficient water is added before entry of the pulp into the conditioning tank to produce a pulp having about 25 percent solids content by weight. While this is the preferable content, Aa solid-liquid ratio up to ll :1 can be used. A pulp density of 1150, in accordance with the Deco Pulp Density Tables, is the preferred pulp density, this rbeing provided by a pulp having about a 25 percent solids content.

The conditioning apparatus used is of the standard type and produces circulation of the pulp -to provide effective mixing. The conditioning tank is provided with steam coils to heat the pulp to the desired temperature. Other means of heating may be used, such as, the introduction of live steam into the pulped ore. The preferred conditioning agent is sodium sulfide and it is used in amounts varying 4from about two to about eight pounds pe-r Iton of ore although the amount may vary from these limits depending upon the type of ore. Other alkaline conditioning agents may be used, such as, sodium hydroxide, sodium carbonate, and other alkali metal sulphides. Sufcient conditioning agent is added to raise the pH to between about 9.5 and about 1l, a preferable pH being 10. The conditioning temperature of the pulp is maintained between about 55 C. and 85 C. with a preferable teniperature being between about 75 C. and about 80 C. The pulp is preferably conditioned for a period of about two to five minutes.

After the conditioning step, the hot pulp at a pH not below about 9.5 is introduced into a standard lot-ation cell preferably at the bottom of the cell accompanied by aeration with air 4introduced at the bottom of the cell. As the pulped ore at a pH lof about and at a temperature between about 75 -80 C. ows from the conditioning 4tank to the flotation cell, oleic acid is introduced dropwise into it at the rate of about 1 d-rop every 6l0 seconds or about 10 drops a minute maxim-um. It is preferable that the oleic acid is added after and not during the conditioning step, and is added just prior to or during the flotation step. Regardlessv Iof the rate of introduction of the conditioned pulp into the otation cell, the maximum amount of oleic acid used must not exceed about 25 grams per ton of ore or a proportionate amount for different a-mounts of ore, .and it is preferably added dropwise to provide .for an even distribution.

During the addition of the oleic acid it is important that the pH be maintained at 9.5 or higher with a maxiiin-um upper limit of about 11. It was found that if the pH drops below 9.5 the oleic acid immediately begins to pick up .gangue materials. This will also occur if the temperature is not maintained within lthe stated range. It is apparent, therefore that there is a critical relationship between temperature, pH range and optimum amounts of oleic acid. This is in contrast to prior art processes, such as that disclosed in the Eigeles et al. article, in which the amounts of oleic acid disclosed as being used are prohibitively excessive for obtaining :a high grade concentrate, and this nodoubt explains why the process disclosed in the article has not gained wide acceptance.

Other fatty lacid collection and flotation agents may be used in place of oleic acid, these materials being referred to herein broadly as fatty acid collection and dotation agents. These include, ifor example; caprylic acid, lauric acid, stearic acid, fish oil acids, tall oil, llinoleic acid, etc.

Aeration of the pulp in combination with the collection and frothing agent results in a .froth containing the beryl which is removed froim the pulp as it reaches the top.

Examples 1-5 below tabulate results obtained using the process of the invention on large scale lots of ore in a production operation. The examples are illustrative of the invention and not limiting thereof.

The ore used in all of the examples came from the Boomer mine of U.S. Beryllium Co. near Colorado Springs, Colorado, and contained beryl, mica, quartz and feldspar, with minor .amounts of tourmaline, hornblende, hematite, topaz, and fluoride. A typical analysis of the ore used in Examples 1 3 showed 2.0 percent BeO, 69.0% sio2, 12.5% A1203, 3.8% Fe, 1.2% Caco, and 1.0% CaF. This ore contained small amounts of bertrandite and euclase.

Example .l

The large scale tests of the following Examples 1 5 were carried out in a flotation mill as schematically illustrated in the drawing wherein a continuous feed of about one ton per hour of ore was fed to a ball mill with enough water to make a pulp of 50% solids. The pulp was pumped to a conditioning tank where it was diluted to 25% solids and heated to 75 C. Sodium sulfide was added at the rate of about 6 pounds per ton of ore, or enough to ob-tain a pH 10 alkalinity. After 5 minutes conditioning the pulp was transferred from the conditioning tank to the first cell of a bank of four flotation cells. Oleic acid was added dropwise at the rate of 30 grams per ton of ore to the pulp between the conditioning tank and the flotation cells.

RES ULTS [Example l] Weight, Weight Weight Dist., Product Tons percent percent, weight BeO percent Beryl concentrate.- 2. 5 26. 3 7. 2 85. 7 Beryl middlings 0. 5 5. 2 3. 4 8. 1 Tails 6. 5 68. 5 0.2 6. 2 Composite 9. 5 100.0 2. 2 100.0

This example was carried out using the same procedure as Example 1 except that only 16 grams of oleic acid were used per ton of ore.

RESULTS Weight, Weight Weight Dist., Product Tons percent percent, weight BeO percent Beryl eoncentrate 3.0 12. 4 12. 2 79. Beryl middlings 0.5 2.1 6.6 7.2 'rens 2o. 7 85. 5 o. 3 13. 5 Composite 24. 2 100. 0 1. 9 100. 0

concentrate when the amount of oleic acid -used is within the critical range.

Example 3 Example 3 using 11.5 tons of ore was carried out with the same procedure as Example 1 except that the froth (or middlings) from reprocessing cells was pumped back to the conditioner and mixed with the pulp from the ball mill and only l2 grams of oleic acid per ton of ore were used.

RES ULTS Weight, Weight Weight Dist., Product Tons percent percent, weight BeO percent Beryl Concentrate- 1. 75 15. 2 ll. 2 83. 5 ailings 9. 75 84. 8 0. 4 16. 5 Composite l1. 50 100. 0 2. 06 100. 0

The beryl'concentrate from the iirst flotation assayed 11.2% BeO and contained 83.5% of the total beryl. The high grade concentrate in Examples 2 and 3 as compared to the low grade concentrate of Example 1, taking into consideration the respective amounts of oleic acid used, illustrate the criticalness of the operative range of the amount of oleic acid.

Example 4 The ore Iused in this example also -contained a small amount of bertrandite with the beryl and assayed 6.09 beryllium oxide. The same procedure and amounts of reagents as was used in Example 4 was used in this example. A concentrate was obtained containing 30.8% beryllium oxide while the tailing assayed 0.4% beryllium oxide indicating an approximate recovery of 94% of the beryllium content of the ore.

The above comparative examples illustrate that the upper range of oleic acid required to iioat only the beryllium minerals -corresponds to a ratio of about 25 grams per ton of ore. It is seen from `the examples that if the amount of oleic acid used in the process of this invention is maintained within the `critical range, concentrates are produced assaying at least BeO and generally in the neighborhood of 12% BeO with a high percentage recovery of beryllium from the ore.

The explanation of the above discovery is not known and is certainly not obvious from prior art teachings, such as, the Eigeles et al. article. It appears, however, that oleic acid exhibits priority selectivity for beryl over the `gangue materials with which it is associated and that it will oait the conditioned beryl particles rst before it oats the gangue materials. Accordingly, it is necessary to use only the maximum critical amount required for flotation of all of the beryl minerals within the critical Itemperature and pH ranges. The dropwise addition of this agent added in the proper sequence of process steps is also of importance.

The invention provides an improved flotation process for the selective flotation of beryllium :minerals from the gangue mineral-s with which they are associated in their ores. The process of the invention produces la high grade marketable concentrate ordinarily having at least a 10% beryllium oxide content |and insures a high percentage yield of beryllium from the ore. The process can be carried out as a continuous operation with a minimum degree of surveillance. Its application .does not require deJslimin-g of the ore as it is effective for selective oating of small particles or beryl. The invention results in an economical use of oleic acid but its chief economical feature is the fact that by its use a high grade concentrate with a high percentage yield of beryllium is obtained in the iirst pass without the necessity of further processing.

Although the invention has been illustrated and described with reference to the preferred embodiments thereof, it is to be understood that it is in no way limited to the details of such embodiments, but is capable of numerous modifications within the scope of the appended claims.

What is claimed is:

1. A process for the concentration of beryllium minerals from an `ore containing them `along with gangue materials which comprises: comminuting the ore t-o a relatively iinely divided state; forming an aqueous pulp of the ore; tre-ating the pulp with from about 2 to 8 pounds per ton of an 'alkaline conditioning yagent selected from the group consisting of alkali metal hydroxides, alkali metal carbonatos and alkali metal sulides at a pH above about 9.5 and at 1a temperature between 'about 55 C. to 90 C.; adding a higher fatty acid colection and flotation agent to the conditioned pulp in an amount not in excess of Iabout 25 grams per ton of ore; and froth floating the beryllium minerals from the gangue materials.

2. A process for the concentration of beryllium minerals from an ore containing them along with gangue materials which comprises: comminuting the ore to a particle size between about minus 50 and minus 100 mesh; forming an aqueous pulp of the ore having la solids content from about 15 to about 60 percent; thoroughly mixing the pulp with from about 4 to -about 6 pounds per ton of ore of an alkaline conditioning agent selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal sulfides at a pH between about 9.5 and 11 at a temperature between about 55 C. to 90 C.; adding 'a higher fatty acid collection and otation agent lto Ithe conditioned pulp in an amount not in excess of 'about 25 grams per ton of ore; and froth floating the beryllium minerals from the gangue materials.

3. The process of claim 2 in which the fatty acid collection 'and notation agent is added along with the conditioning agent.

4. The process of claim 2 in which the alkaline conditioning agent is sodium sulfide.

5. The process of claim 4 in which the amount of added fatty racid collection and flotation agent varies from about 4 to about 25 grams per t0n of ore.

6. A process for the concentration of Iberyllium minerals from an ore containing them along with gangue materials which comprises: comminuting the ore to a particle size in which percent of the particles are minus mesh; forming an aqueous pulp of the ore having a solids content of about 25 percent; thoroughly mixing the pulp with from about 4 to 6 pounds per ton of o-re of an alkali metal sulfide conditioning 'agent at a pH between about 9.5 and 11 at a temperature between about 75 C. -to 80 C.; adding oleic acid asa collection and flotation -agent to the conditioned pulp in an `amount not in excess of about 25 gra-ms per ton of ore; and froth oating the beryllium minerals from the gangue materials.

7. A process for the concentration of a beryllium mineral selected from the class consisting of beryl, phenacite and bertrandite, and mixtures thereof, from an ore in which they are contained along with gangue materials, which comprises: comminuting the ore to a particle size in which 90 percent of the particles are minus 100 mesh; forming an aqueous pulp of the ore having a solids Icontent of about 25 percent; thoroughly mixing the pulp with from about 4 to about 6 pou-nds of sodium sulfide per ton of ore at a pH of about 10 at a temperature between about 75 C. and 80 C.; adding oleic acid to the conditioned pulp in an amount from about 4 to about 25 'grams per ton of ore; and iroth oating the beryllium minerals from the -gangue materials.

S. The process of claim 7 in which the beryllium mineral is beryl.

9. In the process for the concentration of beryllium minerals from ores containing gangue materials in which process an alkali metal sulfide conditioning Iagent is used for conditioning the beryllium min'enal particles for otation and oleic acid is used as a froth notation agent for the beryllium mineral particles, the improvement which comprises reducing said parti-cles to a size not in excess of about minus 50 mesh; adding the oleic acid to the conditioned mineral particles and gangue materials lat a pH between about 9.5 and l1 at a temperature between about 55 C. to 90 C. in an amount not in excess of about 25 grams per ton of ore.

10. The process of claim 9 in which the pH is about 10, 'the temperature is between about 75 C. and 80 C. and the amount of oleic acid added is between about 4 and about 25 ,grams per ton of ore.

11. A process for the concentnation of beryllium minerals from ores containing gangue materials which comprises: comminuting the ore to a particle size in which 90 percent of the particles are minus 100 mesh; forming a Water base pulp of the comminuted ore having about 25 percent solids content; conditioning the pulped ore vat a temperature between about 75 C. to 80 C. by mixing it with Iabout 4 to about 6 pounds of sodium sul-tide per ton of ore as a conditioning agent at a pH between about 9.5 and 1l; flowing the conditioned pulp int-o a flotation cell while introducing intothe pulped and conditioned ore oleic acid at a rate not in excess of about 25 grams per ton of ore; and aerating and froth iolating the beryllium minerals.

12. 'Ilhe process of claim 11 in which the oleic acid is added during the conditioning step.

13. The process of claim 11 in which the oleic acid is added during the froth flotation step.

14. A continuous process for the concentration of beryl from ores containing gangue materials which comprises: wet grinding the ore to ya particle size in which 90 percent of the particles are minus 100 mesh; fonming la water base pulp of Ithe comminuted ore having about a 25 percent solids content; conditioning the pulped ore a-t a temperature between about 75 C. and 80 C. `by mixing it with about 4 to about 6 pounds of sodium sulde per ton of ore as a conditioning agent at a pH between about 9.5 and 11; owing the conditioned pulp into a notation cell while introducing into the pulped and conditioned ore oleic acid at a rate not in excess of about 25 :grains per ton of ore; introducing the pulped and conditioned ore into the bottom of a flotation cell While simultaneously introducing air into it at the bottom of the cell to eiiiect a froth flota-tion of the beryllium minenals.

References Cited by the Examiner UNITED STATES PATENTS 2/1963 Havens 209-167 X OTHER REFERENCES HARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner. 

2. A PROCESS FOR THE CONCENTRATION OF BERYLLIUM MINERALS FROM AN ORE CONTAINING THEM ALONG WITH GANGUE MATERIALS WHICH COMPRISES: COMMINUTING THE ORE TO A PARTICLE SIZE BETWEEN ABOUT MINUS 50 AND MINUS 100 MESH; FORMING AN AQUEOUS PULP OF THE ORE HAVING A SOLIDS CONTENT FROM ABOUT 15 TO ABOUT 60 PERCENT; THOROUGHLY MIXING THE PULP WITH FROM ABOUT 4 TO ABOUT 6 POUNDS PER TON OF ORE OF AN ALKALINE CONDITIONING AGENT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDES, ALKALI METAL CARBONATES AND ALKALI METAL SULFIDES AT A PH BETWEEN ABOUT 9.5 AND 11 AT A TEMPERATURE BETWEEN ABOUT 55*C. TO 90*C.; ADDING A HIGHER 